Exiter

An Exiter adds harmonic distortion to the audio signal. Use it to e.g. bring the lead vocals right to the front of the mix when used subtle.

Neutron from iZotope is a mixing channel strip with EQ, Compressor, Exciter, Transient Shaper and Limiter. The presets and Track Assistant quickly gives you a good starting point and the Masking Meter helps to avoid frequency collisions.